Binder supply apparatus and binder supply method for foundry sand

ABSTRACT

Disclosed is a binder supply apparatus for supplying a liquid binder to foundry sand. The binder supply apparatus comprises: a reservoir tank for reserving the binder therein; a first pump for supplying the binder to the reservoir tank; a temperature adjusting device for adjusting the temperature of the binder in the reservoir tank to a given temperature; a second pump for circulating the binder such that the binder is discharged from the reservoir tank to a circulation passage and then re-suppled to the reservoir tank; a flowmeter for measuring the flow rate of the binder flowing through the circulation passage; and a binder ejection port for ejecting the binder.

TECHNICAL FIELD

The present invention relates to a binder supply apparatus and a bindersupply method for supplying a liquid binder to foundry sand.

BACKGROUND ART

Heretofore, a binder supply apparatus for supplying a liquid binder tofoundry sand has been known from, e.g., the following Patent Document 1.

CITATION LIST Parent Document

Patent Document 1: JP H08-976A

SUMMARY OF INVENTION Technical Problem

Conventionally, in a liquid binder supply apparatus, a flow rate of aliquid binder flowing through a flow passage is measured by a flowmeter.However, because, in a space whose temperature varies, an error inmeasured flow rate increases every time a liquid temperature (thetemperature of the liquid binder) is changed, there was a problem ofbeing unable to measure the flow rate with a high degree of accuracy.

Therefore, the present invention has been made to solve the aboveproblem, and an object thereof is to provide a binder supply apparatusand a binder supply method for foundry sand, capable of keeping a liquidtemperature constant to reduce an error in measured flow rate to therebyperform a highly-accurate flow rate measurement.

Solution to Technical Problem

In order to achieve the above object, according to one aspect of thepresent invention, there is provided a binder supply apparatus forsupplying a liquid binder to foundry sand. The binder supply apparatuscomprises: a reservoir tank for reserving the binder therein; a firstpump for supplying the binder to the reservoir tank; a temperatureadjusting device to adjust a temperature of the binder in the reservoirtank to a given temperature; a second pump for circulating the bindersuch that the binder is discharged from the reservoir tank to acirculation passage and then re-suppled to the reservoir tank; aflowmeter for measuring a flow rate of the binder flowing through thecirculation passage; and a binder ejection port for ejecting the binderto allow the binder to be kneaded with the foundry sand.

Preferably, in the binder supply apparatus of the present invention, theflowmeter is installed in the circulation passage at a positiondownstream of the second pump, wherein the binder supply apparatusfurther comprises a three-way valve installed in the circulation passageat a position downstream of the flowmeter, and configured to switch aflow direction of the binder supplied from the second pump, betweentoward a first side allowing the binder to be supplied to the reservoirtank and toward a second side allowing the binder to be supplied to thebinder ejection port.

Preferably, the binder supply apparatus of the present invention furthercomprises a bypass passage for removing air entrained in the binder, thebypass passage being communicably connected to the circulation passageat a position downstream of the second pump, and the reservoir tank,while bypassing the flowmeter.

Preferably, the binder supply apparatus of the present invention furthercomprises an opening-closing valve installed adjacent to and upstream ofthe binder eject port.

Preferably, in the binder supply apparatus of the present invention, thefoundry sand is core sand for making a core.

In the above binder supply apparatus, the core sand may be core sand formaking an inorganic core.

According to another aspect of the present invention, there is provideda binder supply method for supplying a liquid binder to foundry sand.The binder supply method comprises the steps of: supplying, by a firstpump, the binder to a reservoir tank; circulating, by a second pump, thebinder such that the binder is discharged from the reservoir tank to acirculation passage and then re-suppled to the reservoir tank;adjusting, by a temperature adjusting device, a temperature of thebinder in the reservoir tank to a given temperature; and measuring, by aflowmeter, a flow rate of the binder flowing through the circulationpassage.

Preferably, the binder supply method of the present invention furthercomprises a step of switching, by a three-way valve installed in thecirculation passage at a position downstream of the second pump via theflowmeter, a flow direction of the binder supplied from the second pump,between toward a first side allowing the binder to be supplied to thereservoir tank and toward a second side allowing the binder to besupplied to a binder ejection port.

More preferably, in the above binder supply method, during a time periodduring which the binder supplied from the second pump is ejected fromthe binder ejection port, the flow rate of the binder being suppliedfrom the second pump is measured by the flowmeter to figure out anamount of the binder to be ejected from the binder ejection port, and,in response to ascertaining that the amount of the binder to be ejectedreaches a setup amount set to a value less than a target ejectionamount, the second pump is changed to be operated on a pulse-by-pulsebasis.

More preferably, in the above binder supply method, during any timeperiod except for a time period during which the binder supplied fromthe second pump is ejected from the binder ejection port, the bindersupplied from the second pump is circulatingly supplied to the reservoirtank.

Preferably, in the binder supply method of the present invention, thesecond pump is operated on a pulse-by-pulse basis, wherein a pulseperiod is adjusted to reduce a flow rate per pulse of the binder to besupplied from the second pump.

Effect of Invention

The binder supply apparatus and the binder supply method of the presentinvention make it possible to keep the temperature of the binderconstant, even in a space whose temperature varies. This brings outvarious advantageous effects such as an effect of being able to reducean error in measured flow rate to thereby perform a highly-accurate flowrate measurement.

BRIEF DESCRIPTION OF DRAWINGS

FIGURE is an overall configuration diagram depicting a binder supplyapparatus according to one embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

With reference to the drawings, a binder supply apparatus according toone embodiment of the present invention and a binder supply method foruse with the binder supply apparatus will now be described. Thisembodiment will be described based on an example in which core sand (inthis embodiment, artificial sand) for making an inorganic core is usedas foundry sand, and a liquid binder (in this embodiment, liquid glass)is supplied to the core sand. In the FIGURE, the reference sign 1denotes a storage container (in this embodiment, a metal drum) storing aliquid binder therein.

The storage container 1 is communicably connected to a first pump 3 (inthis embodiment, a pneumatic diaphragm pump) via a pipe 2. The firstpump 3 is communicably connected to an inlet side of a reservoir tank 5via a pipe 4. Upon activation of the first pump 3, the binder stored inthe storage container 1 is supplied to the reservoir tank 5. Two openingand closing valves 6, 7 are installed, respectively, in the pipes 2, 4at positions upstream and downstream of the first pump 3. A thermometer25 (in this embodiment, a thermocouple) is mounted to a sidewall of thereservoir tank 5. This thermometer 25 is operable to measure thetemperature of the binder in the reservoir tank 5. Further, a levelswitch 26 is attached inside the reservoir tank 5. This level switch 26is operable to detect an “empty state” and a “full state” in the insideof the reservoir tank 5.

The binder supply apparatus according to this embodiment is equippedwith a temperature adjusting device 8 for adjusting the temperature ofthe binder in the reservoir tank 5 to a given temperature. Thistemperature adjusting device 8 comprises a liquid circulation unit 8 a,an inlet-side pipe 8 b, two stainless steel corrugated tubes 8 c housedin the reservoir tank 5, and an outlet-side pipe 8 b, wherein acirculating liquid discharged from the liquid circulation unit 8 a issupplied to the corrugated tubes 8 c via the inlet-side pipe 8 b, and,after passing through the corrugated tubes 8 c, returned to the liquidcirculation unit 8 a via the outlet-side pipe 8 b. By repeating suchcirculation of the binder, the temperature of the binder can be adjustedthrough heat exchange conducted in a region of the corrugated tubes 8 c.

Further, an outlet side of the reservoir tank 5 is communicablyconnected to a second pump 10 (in this embodiment, an electromagneticdiaphragm pump) via a pipe 9. The second pump 10 is communicablyconnected to a flowmeter 12 (in this embodiment, a Coriolis flowmeter)via a pipe 11. Upon activation of the second pump 10, the binder isdischarged from the reservoir tank 5. Two opening and closing valves 13,14 are installed, respectively, in the pipes 9, 11 at positions upstreamand downstream of the second pump 10.

The flow meter 12 is communicably connected to an inlet side of athree-way valve 16 via a pipe 15. A first one of two outlets of thethree-way value 16 is communicably connected to the inlet side of thereservoir tank 5 via a pipe 17. The other, second, outlet of thethree-way value 16 is communicably connected to a binder ejection port19 via a pipe 18 forming an ejection passage. The three-way valve 16 isa pneumatically-operated three-way valve. Specifically, the three-wayvalve 16 is configured such that, in response to pilot air supplied froma non-depicted solenoid valve to the three-way valve 16, a flowdirection of the binder supplied from the second pump 10 is switchedbetween toward a first side (the side of the pipe 17) allowing thebinder to be supplied to the reservoir tank 5 and toward a second side(the side of the pipe 18) allowing the binder to be supplied to thebinder ejection port 19.

A check valve 20 and an opening and closing valve 21 are installed inthe pipe 18. The opening and closing valve 21 is installed at a positionadjacent to and upstream of the binder ejection port 19. The opening andclosing valve 21 is configured to be normally closed, and opened inresponse to the pilot air supplied from a non-depicted solenoid valvethereto.

A pipe 22 branching from the pipe 11 to allow the binder to flowparallel to the flowmeter 12, i.e., to bypass the flowmeter 12 iscommunicably connected to the inlet side of the reservoir tank 5. Thispipe 22 forms a bypass passage for removing air entrained in the binder.In the pipe 22, an opening and closing valve 23 is installed in anupstream-side sub-pipe through which the binder flows parallel to theflowmeter 12, and an opening and closing valve 24 is installed in adownstream-side sub-pipe at a position adjacent to the inlet side of thereservoir tank 5.

Next, the operation of the binder supply apparatus according to theabove embodiment and a binder supply apparatus for use with this bindersupply apparatus will be described. At start of operation of the bindersupply apparatus, the opening and closing valves 6, 7, 13, 14 areopened, and the opening and closing valves 23, 24 are closed. Thethree-way valve 16 is set such that the flow direction of the binder isswitched toward the first side allowing the binder to be supplied to thereservoir tank 5.

When the level switch 26 detects that the inside of the reservoir 5 isin the “empty state”, the first pump 3 is activated to supply the binderin the storage container 1 to the reservoir tank 5. On the other hand,when the level switch 26 detects that the inside of the reservoir 5 isin the “full state”, the first pump 3 is deactivated.

Subsequently, the second pump 10 is activated. Thus, the binder isdischarged from the reservoir tank 5, and re-supplied to the reservoirtank 5 via the pipe 17. The binder is circulated in this manner, andthis circulation will be repeated.

During the circulation of the binder, the liquid circulation unit 8 a isoperated to conduct heat exchange in the corrugated tubes 8 c. In thisway, the temperature of the binder in the reservoir tank 5 is adjustedto a given temperature. The binder is continuously circulated during theadjustment, so that it is possible to keep constant the temperature ofthe binder in the reservoir tank 5 and the pipes 9, 11, 15, 17 forming acirculation passage.

Subsequently, the three-way valve 16 is controlled such that the flowdirection of the binder is switched toward the second side allowing thebinder to be supplied to the binder ejection port 19. Then, the openingand closing valve 21 is opened. Thus, the binder is sent to the binderejection port 19 via the pipe 18, and ejected from the binder ejectionport 19. The ejected binder is supplied to a non-depicted kneader.

During a time period during which the binder supplied from the secondpump 10 is ejected from the binder ejection port 19, the flow rate ofthe binder being supplied from the second pump 10 is measured by theflowmeter 12. In this way, the amount of the binder to be ejected fromthe binder ejection port 19 is figured out. Then, in response toascertaining that the amount of the binder to be ejected reaches a setupamount set to a value less than a target ejection amount, the secondpump 10 is changed to be operated on a pulse-by-pulse basis. This makesit possible to finely adjust the amount of binder to be ejected from thebinder ejection port 19 to eject the binder with a high degree ofaccuracy. Here, the term “operating the second pump 10 on apulse-by-pulse basis” means that supply and supply stop of the binderfrom the second pump 10, i.e., discharge and suction of the second pump10, are alternately repeated every a given pulse period (given timeperiod).

Subsequently, when the amount of binder to be ejected reaches the targetejection amount, the opening and closing valve 21 is closed. Then, thethree-way valve 16 is controlled such that the flow direction of thebinder is switched toward the first side allowing the binder to besupplied to the reservoir tank 5. Thus, until ejection of the binderfrom the binder ejection port 19 is performed next, the binder suppliedfrom the second pump 10 is circulated again to keep constant thetemperature of the binder in the reservoir tank 5 and the pipes formingthe circulation passage.

Here, the binder supplied to the non-depicted kneader is kneadedtogether with foundry sand, a powdered binder and others in the kneader,and formed into wet sand. Using this wet sand, an inorganic core is madeby a non-depicted inorganic core-making machine.

The binder supply apparatus according to this embodiment comprises thepipe 22 serving as a bypass passage for removing air entrained in thebinder, as mentioned above. In the binder supply apparatus according tothis embodiment, the binder can be circulated via the pipe 22 at a highspeed, so that it is possible to obtain an advantage of being able toremove air entrained in the binder, at a high speed. During this removalof the air, the opening and closing valves 23, 24 are opened. Thus, thebinder is supplied to the inlet side of the reservoir tank 5 via thepipe 22, without restriction on the flow rate thereof due to theflowmeter 12. During the course of the supply of the binder, airentrained in the binder within the reservoir tank 5 will be removed.

Further, the binder supply apparatus according to this embodiment may beconfigured such that the second pump 10 is operated on a pulse-by-pulsebasis, wherein the pulse period is adjusted to be shortened, to therebyreduce a flow rate per pulse of the binder to be supplied from thesecond pump 10. In this case, the amount of the binder to be restrictedby a relatively narrow passage in the flowmeter 12 can be reduced, sothat it is possible to obtain an advantage of being able to improveefficiency of the second pump 10. Here, the term “pulse period” means anelapsed time from start of a certain pulse through until start of thenext pulse.

More specifically, when the pulse period of the second pump 10 becomeslonger, the flow rate per pulse period of the second pump 10 becomeslarger. Thus, the amount of the binder to be restricted by therelatively narrow passage in the flowmeter 12 is increased, leading todeterioration in efficiency of the second pump 10. Therefore, the secondpump 10 is specifically adjusted to shorten the pulse period of thesecond pump 10. In this case, the flow rate per pulse period of thesecond pump 10 can be reduced, so that the amount of the binder to berestricted by the relatively narrow passage in the flowmeter 12 can alsobe reduced. As a result, it is possible to improve efficiency of thesecond pump 10.

In this embodiment, the flowmeter 12 is installed in the circulationpassage at a position downstream of the second pump 10, and thethree-way valve 16 is installed in the circulation passage at a positiondownstream of the flowmeter 12, wherein the three-way valve 16 isconfigured to switch the flow direction of the binder supplied from thesecond pump 10, between toward the first side allowing the binder to besupplied to the reservoir tank 5 and toward the second side allowing thebinder to be supplied to the binder ejection port 19. This configurationhas the advantage that the binder supplied from the second pump 10 canbe circulatingly suppled to the reservoir tank 5, during any time periodexcept for a time period during which the binder supplied from thesecond pump 10 is ejected from the binder ejection port 19.

Further, the binder is continuously circulated during any time periodexcept for the time period during which the binder is ejected from thebinder ejection port 19, so that there is an advantage of being able tokeep constant the temperature of the binder in the reservoir tank 5 andthe pipes forming the circulation passage, without additionallyinstalling a stirrer or the like.

In this embodiment, the opening-closing valve 21 is installed adjacentto and upstream of the binder eject port 19, so that there is anadvantage of being able to suppress dripping from the binder eject port19.

In the binder supply apparatus according to this embodiment, a material,structure, etc., of each of the pipes is not particularly limited, aslong as it forms a flow passage of the binder. For example, it may be atube or duct member, a hose or the like.

In the above embodiment, when removing air entrained in the binder, boththe opening and closing valves 23, 24 are opened. However, the presentinvention is not limited thereto. That is, only one of the opening andclosing valves 23, 24 may be opened.

Further, although the above embodiment has been described based on anexample in which the binder is supplied to core sand for making aninorganic core, the present invention is not limited thereto. Forexample, the present invention may be applied to a process of making anytype of core other than an inorganic core, as long as the process needsto supply a binder to core sand. Further, the present invention may beapplied to a process of making a mold using green sand, as long as theprocess needs to supply a binder to the green sand. Further, the presentinvention may be applied to a process of making a self-hardening mold,as long as the process needs to supply a binder to self-hardeningfoundry sand.

LIST OF REFERENCE SIGNS

3: first pump

5: reservoir tank

8: temperature adjusting device

10: second pump

12: flowmeter

16: three-way valve

19: binder ejection port

21: opening and closing valve

22: pipe (bypass passage)

1. A binder supply apparatus for supplying a liquid binder to foundrysand, comprising: a reservoir tank for reserving the binder therein; afirst pump for supplying the binder to the reservoir tank; a temperatureadjusting device to adjust a temperature of the binder in reservoir tankto a given temperature; a second pump for circulating the binder suchthat the binder is discharged from the reservoir tank to a circulationpassage and then re-suppled to the reservoir tank; a flowmeter formeasuring a flow rate of the binder flowing through the circulationpassage; and a binder ejection port for ejecting the binder to allow thebinder to be kneaded with the foundry sand.
 2. The binder supplyapparatus according to claim 1, wherein the flowmeter is installed inthe circulation passage at a position downstream of the second pump, andwherein the binder supply apparatus further comprises a three-way valveinstalled in the circulation passage at a position downstream of theflowmeter, and configured to switch a flow direction of the bindersupplied from the second pump, between toward a first side allowing thebinder to be supplied to the reservoir tank and toward a second sideallowing the binder to be supplied to the binder ejection port.
 3. Thebinder supply apparatus according to claim 1, wherein the binder supplyapparatus further comprises a bypass passage for removing air entrainedin the binder, the bypass passage being communicably connected to thecirculation passage at a position downstream of the second pump, and thereservoir tank, while bypassing the flowmeter.
 4. The binder supplyapparatus according to claim 1, wherein the binder supply apparatusfurther comprises an opening-closing valve installed adjacent to andupstream of the binder eject port.
 5. The binder supply apparatusaccording to claim 1, wherein the foundry sand is core sand for making acore.
 6. The binder supply apparatus according to claim 5, wherein thecore sand is core sand for making an inorganic core.
 7. A binder supplymethod for supplying a liquid binder to foundry sand, comprising thesteps of: supplying, by a first pump, the binder to a reservoir tank;circulating, by a second pump, the binder such that the binder isdischarged from the reservoir tank to a circulation passage and thenre-suppled to the reservoir tank; adjusting, by a temperature adjustingdevice, a temperature of the binder in the reservoir tank to a giventemperature; and measuring, by a flowmeter, a flow rate of the binderflowing through the circulation passage.
 8. The binder supply method asrecited in claim 7, wherein the binder supply method further comprises astep of switching, by a three-way valve installed in the circulationpassage at a position downstream of the second pump via the flowmeter, aflow direction of the binder supplied from the second pump, betweentoward a first side allowing the binder to be supplied to the reservoirtank and toward a second side allowing the binder to be supplied to abinder ejection port.
 9. The binder supply method according to claim 8,wherein, during a time period during which the binder supplied from thesecond pump is ejected from the binder ejection port, the flow rate ofthe binder being supplied from the second pump is measured by theflowmeter to figure out an amount of the binder to be ejected from thebinder ejection port, and, in response to ascertaining that the amountof the binder to be ejected reaches a setup amount set to a value lessthan a target ejection amount, the second pump is changed to be operatedon a pulse-by-pulse basis.
 10. The binder supply method according toclaim 8, wherein, during any time period except for a time period duringwhich the binder supplied from the second pump is ejected from thebinder ejection port, the binder supplied from the second pump iscirculatingly supplied to the reservoir tank.
 11. The binder supplymethod according to claim 7, wherein the second pump is operated on apulse-by-pulse basis, and wherein a pulse period is adjusted to reduce aflow rate per pulse of the binder to be supplied from the second pump.